1. Field of the Invention
The present invention relates generally to a shrouded centrifugal impeller, and more specifically to a shrouded impeller with a short axial distance and a high radial blade twist.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Shrouded centrifugal impellers are used in rocket engines to produce high pressures in the liquids being pumped to the combustion chambers. The rocket engine efficiency can be increased by using higher pressures. Higher pump pressures can be produced with higher rotational speeds of the centrifugal impeller. Prior art manufacturing techniques limit the rotational speeds of these centrifugal impellers, and therefore limit the efficiencies.
Shrouded impellers have an axial inlet with a radial outlet with separate fluid passages formed between the blades from the inlet end to the outlet end. Shrouded impellers have historically been difficult to manufacture. Prior art shrouded impellers have been manufactured in which the shrouds are brazed on after the blades and passages have been machined from a stock material. In this process, a separate formed shroud is brazed to the blades to form the enclosed passages. In a brazed centrifugal impeller, the brazed locations are not 100% covered and therefore leakage occurs. Also, the brazed shroud is not strong enough for high speed use of the speeds to produce the higher pressures required for increased rocket engine performance.